1. Field of the Invention
The present invention relates to a print controller, a method and a program for print control, a color conversion table, and a method for determining ink quantity.
2. Description of the Prior Art
With respect to images formed in a printing device, their picture quality largely varies depending on the type of printing media. Therefore, when printing an image, users often choose printing media according to their purpose. There are a large number of variations of printing media. For example, there are media different in gloss, calendered paper and plain paper. Users choose calendered paper for high-picture quality printing of photos or the like, and use plain paper when they do not need the highest picture quality. The plain paper is prone to absorb ink recorded on its surface, and may not give desired color development. For example, ink can be excessively absorbed, and the surface of paper can be exposed.
If much ink is recorded, the calendered paper looks highly glossy. If the quantity of ink recorded is small, the paper is less prone to look glossy, and unevenness can show up in gloss depending on the ink quantity.
Conventionally, clear ink containing no coloring material, disclosed in Japanese Patent Prepublication No. Hei 8(1996)-60059, has been used together with colored ink.
With conventional technologies, clear ink is recorded together with colored ink. Therefore, printing media are prone to be undulated, and ink is prone to blot on printing media.
To cope with this, for printing devices, the upper limit of ink recording rate at which ink can be recorded per unit area is laid down from the various points of view: prevention of undulation in printing media, prevention of blotting of ink, reduction of grainy appearance, prevention of banding, and the like.
However, if clear ink is recorded at a constant ratio to colored ink, a problem arises. When the ink recording rate is high, undulation in the printing medium or blotting of the ink result. No matter how clear ink is recorded, undulation in printing media or blotting of ink occurs if the clear ink is simply recorded with no consideration given on the high ink recording rate side.
In case of calendered paper, the improvement of picture quality is expected by recording clear ink in an area where the colored ink is low in ink quantity. However, with respect to actual printing devices, there are a lot of printing conditions because they are provided with various modes and for other reasons. It used to be difficult to obtain favorable picture quality under various printing conditions simply by prescribing the quantity of clear ink.
More specific description will be given. When a plurality of images are printed under a plurality of printing conditions by a conventional technology, even an area with a small ink quantity is indeed glossy and the picture quality is improved in each image. But, when a plurality of the images are compared, they are different in gloss from one another, and impressions individual images give cannot be unified. Therefore, it is difficult to obtain favorable picture quality in every image.